The disclosure relates generally to wireless communications systems and related networks, such as Universal Mobile Telecommunications Systems (UMTSs), its offspring Long Term Evolution (LTE) and 5th Generation New Radio (5G-NR) described and being developed by the Third Generation Partnership Project (3GPP), and more particularly to dynamically selecting and adjusting energy detection thresholds (EDTs) in uncoordinated radio nodes deploying listen before talk to improve throughput on shared spectrum.
Operators of mobile systems, such as UMTS and its offspring including LTE and LTE-Advanced, are increasingly relying on wireless macrocell radio access networks (RANs) (e.g., traditional cellular base stations), along with wireless small cell RANs in order to deploy, for example, indoor voice and data services to enterprises and other customers. Such small cell RANs typically utilize multiple-access technologies capable of supporting communications with multiple users using radio frequency (RF) signals and sharing available system resources such as bandwidth and transmit power. Evolved universal terrestrial radio access (E-UTRA) is the radio interface of 3GPP's LTE upgrade path for UMTS mobile networks. In these systems, there are different frequencies where LTE (or E-UTRA) can be used, and in such systems, user mobile communications devices connect to a serving system, which is represented by a cell.
For both macrocell RANs and small cell RANs, increasing demands for wireless throughput make access to additional wireless spectrum desirable. Examples of such additional wireless spectrum include unlicensed spectrum, shared spectrum, spectrum licensed from a third party, spectrum associated with citizens broadband radio service (CBRS), and so on. In these cases, spectrum allocation, or channel allocation, may be performed by a technique or procedures that occur independently or semi-independently of a mobile network operator (MNO), such as by a spectrum access system (SAS) for example. In this regard, radio nodes within the RANs may operate in the same wireless channel with neighboring radio nodes, which can result in collisions, or instances in which the neighboring radio nodes communicate at a same time, causing RF interference which impairs wireless communications.
Due to the desire by communications service providers to use shared spectrum, such as unlicensed spectrum, to gain additional bandwidth, potentially without additional licensing costs, mechanisms have been designed and implemented to avoid or reduce RF interference issues, including collisions, with use of shared spectrum. One such mechanism is “Listen Before Talk (LBT).” LBT is a mechanism proposed by the 3GPP for LTE in Unlicensed spectrum (LTE-U) and/or License Assisted Access (LAA) for minimizing RF interferences between two transceivers operating in the same shared channel(s) (e.g., unlicensed channel(s)). In this regard, a transceiver can start signal transmission of a communications signal in a shared channel after verifying that the shared channel is free for use, meaning that another transceiver is not presently transmitting signals in the same shared channel. Before transmission, the transceiver first listens to the activity “on the air” (i.e., on the shared channel where it intends to transmit), or verifies that the shared channel is not occupied by another transmission. If a transmission in the same shared channel is detected, the transmitter postpones its intended transmission until the shared channel is free. When two transceivers coordinate their activity through use of LBT, each transceiver will have a certain likelihood of finding transmission opportunities where a shared channel is free for transmission signals. Radio nodes incorporating LBT set an EDT at which the radio node “hears” traffic on the shared channel. In other words, if the radio node detects wireless signals at an energy level which exceeds the EDT, the channel is determined to be occupied and the radio node waits before communicating over the channel.
In this regard, FIG. 1 illustrates two neighboring radio nodes 100(1), 100(2) having different EDTs. A first radio node 100(1) has a higher EDT, such that it will only “hear” (e.g., respond to) radio signals which exceed a defined high EDT, represented here as a relatively small listening range 102(1). A second radio node 100(2) has a lower EDT than the first radio node 100(1), such that the second radio node 100(2) will hear radio signals exceeding a defined low EDT, represented here as a relatively large listening range 102(2). The listening range 102(1) of the first radio node 100(1) indicates that the first radio node 100(1) only hears signals which originate within the listening range due to its higher EDT. Accordingly, because of the higher EDT, the first radio node 100(1) does not hear signals from the second radio node 100(2), and while employing LBT the first radio node 100(1) will transmit signals even if the second radio node 100(2) is transmitting over the same channel. However, the listening range 102(2) of the second radio node 100(2) indicates that due to its lower EDT, the second radio node 100(2) hears signals from the second radio node 100(2), and while employing LBT the second radio node 100(2) will not transmit signals if the first radio node 100(1) is transmitting over the same channel.
In this manner, the second radio node 100(2) having a lower EDT can ensure that the second radio node 100(2) does not transmit when its transmissions might interfere with the first radio node 100(1) (e.g., a neighboring radio node), which can improve signal quality while reducing the amount of time the second radio node 100(2) occupies the shared channel. In contrast, a higher EDT can enable the first radio node 100(1) to occupy the same channel as the second radio node 100(2) (e.g., a neighboring radio node), increasing the amount of time the first radio node 100(1) occupies the channel while decreasing signal quality. Standards such as LTE-U or LAA may set a limit to the EDT (e.g., a maximum EDT value), but may otherwise allow radio nodes operating within the standard to set lower EDT values.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.